This patch fixes the case where an expire returns busy on a tree
mount when it is in fact not busy. This case was overlooked when
the patch to prevent the expiring away of "scaffolding" directories
for tree mounts was applied.
The problem arises when a tree of mounts is a member of a map
with other keys. The current logic will not expire the tree if
any other mount in the map is busy. The solution is to maintain
a "minimum" use count for each autofs dentry and compare this
to the actual dentry usage count during expire.
Signed-off-by: Ian Kent <[email protected]>
--- linux-2.6.15-mm3/fs/autofs4/inode.c.expire-tree-false-negative 2006-01-13 16:05:10.000000000 +0800
+++ linux-2.6.15-mm3/fs/autofs4/inode.c 2006-01-13 16:17:08.000000000 +0800
@@ -46,6 +46,7 @@ struct autofs_info *autofs4_init_ino(str
ino->size = 0;
ino->last_used = jiffies;
+ atomic_set(&ino->count, 0);
ino->sbi = sbi;
@@ -64,10 +65,19 @@ struct autofs_info *autofs4_init_ino(str
void autofs4_free_ino(struct autofs_info *ino)
{
+ struct autofs_info *p_ino;
+
if (ino->dentry) {
ino->dentry->d_fsdata = NULL;
- if (ino->dentry->d_inode)
+ if (ino->dentry->d_inode) {
+ struct dentry *parent = ino->dentry->d_parent;
+ if (atomic_dec_and_test(&ino->count)) {
+ p_ino = autofs4_dentry_ino(parent);
+ if (p_ino && parent != ino->dentry)
+ atomic_dec(&p_ino->count);
+ }
dput(ino->dentry);
+ }
ino->dentry = NULL;
}
if (ino->free)
--- linux-2.6.15-mm3/fs/autofs4/root.c.expire-tree-false-negative 2006-01-13 16:13:33.000000000 +0800
+++ linux-2.6.15-mm3/fs/autofs4/root.c 2006-01-13 16:17:08.000000000 +0800
@@ -490,6 +490,7 @@ static int autofs4_dir_symlink(struct in
{
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
+ struct autofs_info *p_ino;
struct inode *inode;
char *cp;
@@ -523,6 +524,10 @@ static int autofs4_dir_symlink(struct in
dentry->d_fsdata = ino;
ino->dentry = dget(dentry);
+ atomic_inc(&ino->count);
+ p_ino = autofs4_dentry_ino(dentry->d_parent);
+ if (p_ino && dentry->d_parent != dentry)
+ atomic_inc(&p_ino->count);
ino->inode = inode;
dir->i_mtime = CURRENT_TIME;
@@ -549,11 +554,17 @@ static int autofs4_dir_unlink(struct ino
{
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
+ struct autofs_info *p_ino;
/* This allows root to remove symlinks */
if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
return -EACCES;
+ if (atomic_dec_and_test(&ino->count)) {
+ p_ino = autofs4_dentry_ino(dentry->d_parent);
+ if (p_ino && dentry->d_parent != dentry)
+ atomic_dec(&p_ino->count);
+ }
dput(ino->dentry);
dentry->d_inode->i_size = 0;
@@ -570,6 +581,7 @@ static int autofs4_dir_rmdir(struct inod
{
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
+ struct autofs_info *p_ino;
if (!autofs4_oz_mode(sbi))
return -EACCES;
@@ -584,8 +596,12 @@ static int autofs4_dir_rmdir(struct inod
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
+ if (atomic_dec_and_test(&ino->count)) {
+ p_ino = autofs4_dentry_ino(dentry->d_parent);
+ if (p_ino && dentry->d_parent != dentry)
+ atomic_dec(&p_ino->count);
+ }
dput(ino->dentry);
-
dentry->d_inode->i_size = 0;
dentry->d_inode->i_nlink = 0;
@@ -599,6 +615,7 @@ static int autofs4_dir_mkdir(struct inod
{
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
+ struct autofs_info *p_ino;
struct inode *inode;
if ( !autofs4_oz_mode(sbi) )
@@ -621,6 +638,10 @@ static int autofs4_dir_mkdir(struct inod
dentry->d_fsdata = ino;
ino->dentry = dget(dentry);
+ atomic_inc(&ino->count);
+ p_ino = autofs4_dentry_ino(dentry->d_parent);
+ if (p_ino && dentry->d_parent != dentry)
+ atomic_inc(&p_ino->count);
ino->inode = inode;
dir->i_nlink++;
dir->i_mtime = CURRENT_TIME;
--- linux-2.6.15-mm3/fs/autofs4/autofs_i.h.expire-tree-false-negative 2006-01-13 16:13:33.000000000 +0800
+++ linux-2.6.15-mm3/fs/autofs4/autofs_i.h 2006-01-13 16:17:08.000000000 +0800
@@ -54,6 +54,7 @@ struct autofs_info {
struct autofs_sb_info *sbi;
unsigned long last_used;
+ atomic_t count;
mode_t mode;
size_t size;
--- linux-2.6.15-mm3/fs/autofs4/expire.c.expire-tree-false-negative 2006-01-13 16:16:14.000000000 +0800
+++ linux-2.6.15-mm3/fs/autofs4/expire.c 2006-01-13 16:19:37.000000000 +0800
@@ -101,6 +101,7 @@ static int autofs4_tree_busy(struct vfsm
unsigned long timeout,
int do_now)
{
+ struct autofs_info *ino;
struct dentry *p;
DPRINTK("top %p %.*s",
@@ -110,14 +111,6 @@ static int autofs4_tree_busy(struct vfsm
if (!simple_positive(top))
return 1;
- /* Timeout of a tree mount is determined by its top dentry */
- if (!autofs4_can_expire(top, timeout, do_now))
- return 1;
-
- /* Is someone visiting anywhere in the tree ? */
- if (may_umount_tree(mnt))
- return 1;
-
spin_lock(&dcache_lock);
for (p = top; p; p = next_dentry(p, top)) {
/* Negative dentry - give up */
@@ -130,17 +123,40 @@ static int autofs4_tree_busy(struct vfsm
p = dget(p);
spin_unlock(&dcache_lock);
+ /*
+ * Is someone visiting anywhere in the subtree ?
+ * If there's no mount we need to check the usage
+ * count for the autofs dentry.
+ */
+ ino = autofs4_dentry_ino(p);
if (d_mountpoint(p)) {
- /* First busy => tree busy */
if (autofs4_mount_busy(mnt, p)) {
dput(p);
return 1;
}
+ } else {
+ unsigned int ino_count = atomic_read(&ino->count);
+
+ /* allow for dget above and top is already dgot */
+ if (p == top)
+ ino_count += 2;
+ else
+ ino_count++;
+
+ if (atomic_read(&p->d_count) > ino_count) {
+ dput(p);
+ return 1;
+ }
}
dput(p);
spin_lock(&dcache_lock);
}
spin_unlock(&dcache_lock);
+
+ /* Timeout of a tree mount is ultimately determined by its top dentry */
+ if (!autofs4_can_expire(top, timeout, do_now))
+ return 1;
+
return 0;
}
-
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